Camouflaged, they move through the thickets and brushes of the wild, guiding their allies or tracking their enemies. Rangers are the insightful and skillful agents of their realms, from underworlds to mountain tops. Their tool-belt is a repertoire of spells, traps, beasts, and weapons. When you need someone to help get you somewhere, or to get away from someone, you want a Ranger.
D&D 5E has many sub-classes to choose from, spanning several core books. Here are some quick summaries of each subclass, which will give a bit of insight to the theme, generalized game mechanics, and the likely play style to expect. This list isn’t the way you are expected to play the subclass, but our own interpretation of what the subclass archetype is trying to be. Your interpretation may differ, and if it does, please share how!

Hunter (Player’s HandBook)
Theme: Hunters will seek down anyone or anything. Whether it be a horde or a colossal giant, they can find it and know how to defeat it.
Game Mechanics: Varying choices for combat bonuses, typically focused on either a single foe or a group. Later levels will revolve around defensive and area of effect attacks.
Play-style: “Just shoot it” play-style is easiest with the hunter, and they will dish out high damage! Best to pick if you want to emphasize the favored enemy and terrain.

Beast Master (PHB)
Theme: Travels with their best friend, a creature of the wilds. The teeth and claw of their friend is just as much a weapon as their bow or blade.
Game Mechanics: Gets a beast companion, which can engage in combat and gains further attack bonuses as you level.
Play-style: You love having pets so much that you don’t want to leave them, ever. They join you in combat, on hikes, and at every meal.

Gloom Stalker (Xanathar’s Guide to Everything)
Theme: Hunt those that hide in the shadows by becoming the shadow yourself. If you want to ambush the ambusher, you want the gloom stalker.
Game Mechanics: They have a lot of bonuses for the first round of combat. Spells are catered to disguising yourself, turning invisible, or setting up ambushes.
Play-style: You like the thrill of the hunt, but you like luring your enemies into your traps even more.

Horizon Walker (XGE)
Theme: Beyond forests, lakes, and the underworld, the planes of existence are the unexplored frontier, and the horizon walkers are the pioneers.
Game Mechanics: Additional spells such as protection, misty step, and haste add to the planar theme. Able to passively sense portals, do additional force damage on attacks, and step into etheral planes to move faster.
Play-style: You’re interested in the unknown planes of existence. You love to weave in and out of time and space in order to achieve your goals.

Monster Slayer (XG)
Theme: Anyone and anything can be a monster, and the monster slayer prepares to investigate, track, and engage every possibility to gain the upper hand.
Game Mechanics: Able to identify immunities, resistances, and vulnerabilities, and do additional damage to those that they focus on. At higher levels they gain further defensive abilities, counter spelling, and counter attacks
Play-style: You want to be the jack-of-all-trades of combat. It’s fun to role play the hunter with a wise sage twist.

Drakewarden (FTD)
Theme: An expert in dragons, the drakewarden is so familiar with dragons that they can summon a drake companion.
Game Mechanics: Start off with the Thaumaturgy cantrip and know the Draconic language. Also begin being able to summon a drake companion, which has its own stat block associated with acid, cold, fire, lightning, or poison. The companion acts like a draconic-dog. At level 7, your drake companion can fly, deals extra damage, and you gain resistance to the type of drake you choose. At 11th level, you or your drake companion can now do a dragon breath attack. Finally, at level 15, you and your drake can gain resistance to any damage. Your drake also deals additional damage, grows in size, and can now be mounted and fly.
Play-style: You have always wanted to find a dragon egg to have a dragon pet.